Primary renal synovial sarcoma presenting with tumor rupture and extensive intra-abdominal dissemination: A case report and literature review.

Primary renal synovial sarcoma is a rare malignant mesenchymal neoplasm that may pose significant diagnostic challenges. We report a 34-year-old man who presented with recurrent hemorrhage and hemoperitoneum from a large left renal mass. Following embolization and multivisceral resection, histologic examination revealed a high-grade spindle and round cell neoplasm initially favored to represent Ewing sarcoma. Molecular analysis identified an SS18SSX2 fusion, establishing the diagnosis of poorly differentiated synovial sarcoma. This case highlights the importance of molecular testing and raises the possibility that tumor rupture may contribute to atypical intra-abdominal dissemination.